\input pstfig
$
\def\myR{1.8}
\def\myr{0.6}
\def\myH{4.7}
\pnode(0,0){O}
\pnode(\myR, 0){A}
\pnode(-\myR, 0){B}
\pnode(0, \myH){S}
%\psellipse[angleA=180,angleB=0](O)(\myR, \myr)
\psellipticarc(O)(\myR, \myr){180}{0}
\psline(A)(S)(B)
\noneline
\pcline(S)(B)
\Bput{l}
\thinline
\dashline
\psellipticarc(O)(\myR, \myr){0}{180}
\pcline(S)(O)
\psset{labelsep=0.2ex}
\Aput{H}
\pcline(O)(A)
\nLput[offset=-1.2ex](O)(A){0.4}{R}
$
\bye
